Thread (22 messages) 22 messages, 6 authors, 2021-09-29

Re: [RFC] arm64: mm: update max_pfn after memory hotplug

From: Will Deacon <will@kernel.org>
Date: 2021-09-29 10:10:43
Also in: linux-mm, lkml

On Thu, Sep 23, 2021 at 03:54:48PM -0700, Chris Goldsworthy wrote:
quoted hunk ↗ jump to hunk
From: Sudarshan Rajagopalan <redacted>

After new memory blocks have been hotplugged, max_pfn and max_low_pfn
needs updating to reflect on new PFNs being hot added to system.

Signed-off-by: Sudarshan Rajagopalan <redacted>
Signed-off-by: Chris Goldsworthy <redacted>
---
 arch/arm64/mm/mmu.c | 5 +++++
 1 file changed, 5 insertions(+)
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index cfd9deb..fd85b51 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -1499,6 +1499,11 @@ int arch_add_memory(int nid, u64 start, u64 size,
 	if (ret)
 		__remove_pgd_mapping(swapper_pg_dir,
 				     __phys_to_virt(start), size);
+	else {
+		max_pfn = PFN_UP(start + size);
+		max_low_pfn = max_pfn;
+	}
We use 'max_pfn' as part of the argument to set_max_mapnr(). Does that need
updating as well?

Do we have sufficient locking to ensure nobody is looking at max_pfn or
max_low_pfn while we update them?

Will

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